RHEL Postgres Block sizes OS/Database

Hello Chris, 

PGSQL on RHEL should work just fine as it is with default settings. Most filesystems default to 4k or smaller block sizes, so that's what PG is accustomed to run on.

Additionally, you can also check the same with a PGSQL dba as per the below article:

https://community.progress.com/s/article/18293

If the OS block size is 4K and the database has an 8 KB database block size:

• The OS will need to perform 2 physical I/O's for every database block read.
• However there will be a benefit regarding index blocks. With larger index blocks more keys can be stored in a single block, so less block reads need to be performed to find specific keys.
• Similarly, more records can be stored in a single block when the area is configured with the best records per block for the content. This can have a dramatic performance benefit on system i/o performance.

If the filesystem block size can be changed to 8 KB, there will be a benefit all around (assuming the database block size is also changed to 8 KB).  An 8 KB block size will generally give better performance than 4 KB if the records per block have been correctly configured for the content. There are exceptions, such as if the average record size is very small and there are many of these records when the records per block are set too low.

Thanks, 

Shikhil Bhatia